Bierce was born in a log cabin at Horse Cave Creek in Meigs County, Ohio, on June 24, 1842, to Marcus Aurelius Bierce (1799–1876) and Laura Sherwood Bierce. He was of entirely English ancestry: all of his forebears came to North America between 1620 and 1640 as part of the Great Puritan Migration. He often wrote critically of both "Puritan values" and people who "made a fuss" about genealogy. He was the tenth of thirteen children, all of whom were given names by their father beginning with the letter "A": in order of birth, the Bierce siblings were Abigail, Amelia, Ann, Addison, Aurelius, Augustus, Almeda, Andrew, Albert, Ambrose, Arthur, Adelia, and Aurelia. His mother was a descendant of William Bradford.
His parents were a poor but literary couple who instilled in him a deep love for books and writing. Bierce grew up in Kosciusko County, Indiana, attending high school at the county seat, Warsaw.
He left home at 15 to become a printer's devil at a small abolitionist Ohio newspaper, the Northern Indianan.